Seasonal assessment of the distribution, source apportionment, and risk of water-contaminated polycyclic aromatic hydrocarbons (PAHs).

The research aims to evaluate the seasonal differences in the distribution, source, and risks of water-contaminated PAHs. The PAHs were extracted by the liquid-liquid method and analyzed with GC-MS, and a total of eight PAHs were detected. There was a percentage increase in the average concentration of the PAHs from the wet to the dry season in the range of 20 (Anthracene)-350 (Pyrene)%. Total PAHs (∑PAHs) range from 0.31 to 1.23 mg/l in the wet period and from 0.42 to 1.96 mg/l in the dry period. The distribution of the average PAHs in mg/l showed that Fluoranthene ≤ Pyrene < Acenaphthene < Fluorene < Phenanthrene < Acenaphthylene < Anthracene < Naphthalene in wet period and while Fluoranthene < Acenaphthene < Pyrene < Fluorene < Phenanthrene < Acenaphthylene < Anthracene < Naphthalene in the dry period. The children were exposed to non-carcinogenic risk through non-dietary ingestion due to the accumulative effect (HI) of the PAHs in the dry period. Furthermore, the naphthalene was responsible for ecological and carcinogenic risk in the wet period, while the fluorene, phenanthrene, and anthracene were responsible for ecological and carcinogenic risk in the dry period. However, while adults and children are both susceptible to carcinogenic risk through the oral channel during the dry period, only children are susceptible to non-carcinogenic risk through this pathway. The multivariate statistical analysis revealed the influence of physicochemical parameters on the detected PAHs and also showed the PAHs' sources to be mainly combustion, pyrolysis, and vehicular emission.

[Preparation and application of graphene oxide functionalized melamine-formaldehyde aerogel coated solid-phase microextraction tube].

Many solid-phase microextraction (SPME) sorbents have been developed from aerogels because of their low densities, large surface areas, and high porosities. Melamine-formaldehyde (MF) aerogel, made from melamine and formaldehyde by a sol-gel reaction, is one of the typical organic aerogels. MF aerogel has better mechanical strength, chemical stability and extraction performance than inorganic aerogels. The performance of the aerogel is limited in some fields, while composite aerogels can meet different requirements such as good mechanical strength and strong adsorption performance. Graphene oxide (GO) is a two-dimensional nanomaterial composed of a single layer of carbon atoms and provides π-π interaction by a large π-electron. In addition, the oxygen-containing groups at the edge of the lamellar structure improve the hydrophilicity of the material and can interact with various compounds. To improve the extraction performance of MF aerogel for polycyclic aromatic hydrocarbons (PAHs), GO/MF aerogels were prepared by functionalizing MF aerogel with GO. In this study, 1.2612 g of melamine and 80 mg of sodium carbonate were dissolved in 30 mL of water, and the mixture was heated to 80 ℃ under stirring. Then, 2.8 mL formaldehyde solution (37%) was slowly added, and a clear solution was obtained gradually. Next, 50 mg of GO powder was ultrasonically dispersed in 10.0 mL of water and evenly mixed with the above solution. After adjusting the pH to 1.5, the sol-gel process was performed for 48 h, then the gel was aged at room temperature for 24 h. The gel was then soaked in ethanol, acetone, and cyclohexane in turn to replace the solvent. Finally, the GO/MF aerogel was obtained by freeze-drying for 24 h. The GO/MF aerogel was characterized by scanning electron microscopy (SEM) and X-ray photoelectric spectroscopy (XPS), confirming that GO was successfully introduced into MF aerogel, while retaining its three-dimensional network and porous structure. GO/MF aerogel was coated onto the surface of a stainless steel wire to be used as sorbent. Four such wires were placed into a polyetheretherketone (PEEK) tube (0.75 mm i. d., 30 cm length) for in-tube (IT) SPME. The tube was combined with a high-performance liquid chromatography (HPLC) unit to construct an IT-SPME-HPLC online system. When the six-way valve was in the Load state, sample solution achieved online enrichment with analytes while it flowed through the extraction tube. After extraction, the valve was turned to the Inject state, and the analytes were eluted into the chromatographic column by the mobile phase at a flow rate of 1.0 mL/min for separation and detection with the detector. Under the same extraction conditions (sampling volume=30 mL, sampling rate=1.00 mL/min, and concentration of polycyclic aromatic hydrocarbons (PAHs, viz. naphthalene (Nap), acenaphthylene (Acy), acenaphthene (Ace), fluorine (Flu), phenanthrene (Phe), anthracene (Ant), fluoranthene (Fla) and pyrene (Pyr))=5.00 µg/L), GO/MF aerogel-based tube was compared with that of MF aerogel-based tube. GO enhanced the enrichment efficiency of MF aerogel towards PAHs from 1.1 to 2.5 times, due to the increased number of adsorption sites and enhanced π-π interaction with PAHs. IT-SPME was affected by the sampling volume, sampling rate, concentration of organic solvent in sample, desorption solvent, desorption rate, and desorption time. To obtain accurate results, the main extraction and desorption conditions (sampling volume, sampling rate, organic solvent concentration, desorption time) were investigated carefully. As the sampling volume in the extraction tube was increased, the extraction efficiency was found to increase gradually until saturation. In this study, the extraction efficiency was investigated for sampling volumes ranging from 30 to 80 mL, and 70 mL was selected as a suitable sampling volume to achieve satisfactory extraction efficiency. The sampling rate affects not only the extraction efficiency, but also the extraction time. When the sample flows through the extraction tube at a low rate, it requires a long test time. Although the increase in sampling rate reduces the extraction time, it often decreases extraction efficiency. In addition, large sampling rate leads to high pressure in the tube, which in turn reduces the service life of the tube. Therefore, the effect of sampling rate (1.25-2.50 mL/min) on extraction efficiency was investigated, and good extraction efficiency and short test time were achieved when the sampling rate was 2 mL/min. High hydrophobic PAHs have poor solubility in water. An appropriate amount of organic solvent in the sample solution can improve the solubility of PAHs to obtain accurate analytical results. However, the extraction efficiency was affected by the added organic solvent. Thus, the effect of volume fraction of methanol (0, 0.5%, 1%, 2%, 3%, and 5%, v/v) on the extraction efficiency was investigated. The sample solution without methanol afforded better extraction efficiency and satisfactory repeatability. After online extraction, the desorption directly affects the desorption efficiency. The peak areas of the eight PAHs were investigated with different desorption times (0.2, 0.4, 0.6, 0.8, 1.0, and 2.0 min), and a desorption time of 2.0 min was required to fully desorb all analytes and reduce their residuals. The IT-SPME-HPLC-DAD method was established under the optimized conditions, and the limits of detection (LODs), linear equations, linear ranges, and correlation coefficients were obtained. The LODs of the eight PAHs were in the range of 0.001-0.005 µg/L, the quantitative ranges of the analytes were 0.003-15.0 µg/L for Fla and Pyr, 0.010-20.0 µg/L for Phe and Ant, and 0.017-20.0 µg/L for Nap, Acy, Ace and Flu, the enrichment factors were in the range of 2029-2875, and the analytical precision was satisfactory (intra-day RSD%≤4.8%, and inter-day RSD≤8.6%). Compared with some reported methods, the method reported herein provided higher sensitivity, wider linear range, and shorter test time. This method was applied to the detection of PAHs in common drinking water, including bottled mineral water and water from drinking fountain. The satisfactory recovery (76.3%-132.8%) obtained proves that the method is suitable for the determination of trace PAHs in real water samples, with high sensitivity, rapid testing, online detection, and good accuracy. The extraction tube also exhibited satisfactory durability and chemical stability.

Hydrophobic microporous extraction on polyurethane sponges for convenient and sensitive analysis of organic molecules in water.

RATIONALE: Various solvent supports have been developed to overcome solvent instability during liquid-phase microextraction. The hydrophobic polyurethane sponge (PS) possesses numerous cross-linked internal microchannels and terminal micropores that can facilitate steady solvent storage capacity, high extraction efficiency, extractant loading, and recycling convenience. METHODS: In this study, an easy, convenient, and efficient PS-supported liquid-phase microextraction (PS-LPME) coupled with gas chromatography-mass spectrometry (GC-MS) method was developed for the trace analysis of different organic compounds in aqueous solutions. Different extraction solvents, PS dosages, stirring speeds, and extraction times were first investigated by extracting eight polycyclic aromatic hydrocarbons (PAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene), and then applied for the analysis of triazines, amides, chloroacetamides, and organophosphorus compounds. RESULTS: High enrichment factors (approximately 208-439) were observed for the monitored PAHs. Good linearities, with determination coefficients (r2 ) greater than 0.9992, were achieved in the concentration range of 0.01-50 µg L-1 . Low limits of detection and quantification were found in the ranges of 0.3-3 ng L-1 and 1-10 ng L-1 , respectively. At three spiked concentrations (0.1, 1, and 10 µg L-1 ), good recoveries were obtained in the range of 91.6-118.5% with intra- and inter-day relative standard deviations of less than 6.4% and 11.7%, respectively. CONCLUSIONS: The developed PS-LPME method coupled with GC-MS was successfully applied in the analysis of different organic compounds in aqueous solutions and has shown great convenience and satisfactory enrichment performance in microextraction analysis.

Environmental complex exposure and the risk of influenza-like illness among housewives: A case study in Shanxi Province, China.

The association between environmental pollution and risk of influenza-like illness (ILI) among general population has been reported. However, the relationships between the individual pollutants and ILI risk are still under discussion. Our study aimed to explore the associations of the typical environmental polycyclic aromatic hydrocarbons (PAHs) and metal(loid)s with ILI risk among women population. We carried out a cross-sectional study and included a total of 396 housewives in Shanxi Province, China. The information on their general characteristics and ILI frequency was collected by questionnaire. We collected their hair samples and analyzed the concentrations of PAHs and various metal(loid)s. The results indicated that only acenaphthylene concentration of the nine detected PAH congeners in the hair was significantly associated with ILI risk with adjusted odds ratio (AOR) and 95% confidence interval (95% CI) of 0.58 (0.38 - 0.91). Among the concerned 4 toxic metal(loid)s and 15 rare earth elements, only the hair concentration of arsenic had a positive dose-response relationship with ILI risk. In addition, we found that there were negative dose-response associations of the three essential trace elements (i.e. chromium, cobalt, and nickel), and four essential alkaline earth elements (i.e. magnesium, calcium, strontium, barium) with ILI risk. It was concluded that the environmental exposure to certain compounds of housewives may contribute to their ILI development.

Investigation of geospatial distribution of PAH compounds in soil phase and determination of soil-air exchange direction in a megacity.

In this study, determination of possible sources, soil-air exchange direction, and spatial distribution of PAH concentrations was aimed. In this scope, soil samples were collected from 35 different points, which have the urban and rural characteristics, from European and Asian Sides in Istanbul. The average ∑16PAH concentrations were found as 22.11 ng/g dw for urban site and 19.53 ng/g dw for rural site, respectively. The highest concentration was 279.5 ng/g dw. PAH concentrations were higher in urban site than rural site. Acenaphthene and benzo[k]fluoranthene were observed as the dominant species. PAH concentrations are observed higher mostly in north and west parts of European Side and south and east parts of Asian Side. There was net evaporation from soil to air for lower molecular weight PAHs with 2, 3 rings, while high molecular weight PAHs with 4, 5, 6 rings accumulated in the soil at both urban and rural sites. PAHs were mostly originated from coal burning and the use of diesel engine vehicles.

Assessment of concentration of polycyclic aromatic hydrocarbons (PAHs) in vegetables from farms in Accra, Ghana.

Ingestion of leafy vegetables is an important dietary component of most Africans due to its health benefits. High levels of polycyclic aromatic hydrocarbons (PAHs) in the leafy vegetables may pose a significant health hazard to the consumers. Rose/Hibiscus, Chinese cabbage, lettuce, and garden egg leaves from farms along the Nima Creek, Accra, were selected. At each sampling site, the vegetable was uprooted and cut into leaves, stem, and root and analyzed differently. The GC-MS method was employed in the identification and quantification of 16 PAHs in the samples. The analysis was done at CSIR - Water Research Institute Organic Laboratory. The results obtained show concentrations of acenapththylene, acenapthene, benzo[a]anthracene, benzo[b]fluoranthene, and benzo[a]pyrene (except chrysene and pyrene which were found in garden egg leaves and Chinese cabbage respectively), while naphthalene was detected in all the vegetables. The mean concentration of phenanthrene in leaves, stem, and roots of Chinese cabbage vegetable varies according to the following order: roots (0.744 ± 0.16 µg/kg) ≥ leaves (0.598 ± 1.21 µg/kg) ≥ stem (0.327 ± 1.01 µg/kg). From the results of the isomeric ratios, the source of the PAHs in the leafy vegetables are from mixed sources, i.e., either pyrogenic and petrogenic origins. This calls for the formulation of stringent policies on the importation of over-age vehicles into the countries as well as on the indiscriminate burning of materials containing PAHs.

Association of polycyclic aromatic hydrocarbons in housewives' hair with hypertension.

The relationship between polycyclic aromatic hydrocarbons (PAHs) and hypertension remains a subject of debate. The aims of this study were to determine an association of concentrations of PAHs in housewives' hair with hypertension risk and the modification effect of single nucleotide polymorphisms (SNPs) related to Phase I metabolism of PAHs. We recruited 405 women for a cross-sectional study in Shanxi Province, China, including 170 with hypertension (the case group) and 235 without hypertension (the control group). We analyzed 26 individual PAHs in hair samples and the SNPs of the genes including cytochrome P450, family 1, subfamily A, polypeptide 1 (CYP1A1), CYP1A2, CYP1B1 and CYP2E1. Our results showed that seven PAHs in hair samples were measured with detection rate >70%. Only acenaphthylene was found to be associated with an increased risk of hypertension with adjustment for the potential confounders following Bonferroni correction, whereas others not. No SNPs of the concerned genes were found to be associated with the risk of hypertension. A multiple interaction effect of PAHs in housewives' hair and SNPs on hypertension risk was not observed. It was concluded that PAHs tended to contribute to the formation of hypertension.

Polycyclic aromatic hydrocarbons (PAHs) in yogurt samples.

The concentrations and distributions of major polycyclic aromatic hydrocarbons (PAHs) were determined in 20 kinds of yogurt specimens collected from Italian supermarkets using reversed phase high-performance liquid chromatography equipped with fluorescence detection. The method was validated by determination of recovery percentages, precision (repeatability) and sensitivity (limits of detection) with yogurt samples fortified at 0.25, 0.5 and 1 µg/kg concentration levels. The recovery of 13 PAHs, with the exception of naphthalene and acenaphthene, ranged from 61% to 130% and from 60% to 97% at all the levels for yogurts with low (0.1%) and high (3.9%) fat content, respectively. The method is repeatable with relative standard deviation values <20% for all analytes. The results obtained demonstrate that acenaphthene, fluorantene, phenanthrene, anthracene, fluoranthene and pyrene were found in all samples with a similar distribution, but different content when yogurts with low and high fats were compared.

Development of a new sorptive extraction method based on simultaneous direct and headspace sampling modes for the screening of polycyclic aromatic hydrocarbons in water samples.

A new straightforward and inexpensive sample screening method for both EPA and EU priority polycyclic aromatic hydrocarbons (PAHs) in water has been developed. The method is based on combined direct immersion and headspace (DIHS) sorptive extraction, using low-cost disposable material, coupled to ultraperformance liquid chromatography with fluorescence and UV detection (UPLC-FD-UV). Extraction parameters, such as the sampling mode, extraction time and ionic strength were investigated in detail and optimized. Under optimized conditions, water samples (16 mL) were concentrated in silicone disks by headspace (HS) and direct immersion (DI) modes simultaneously, at room temperature for 9h for the majority of the 24 studied compounds. Ultrasound-assisted desorption of extracted analytes in acetonitrile was carried out also at room temperature. The optimized chromatographic method provided a good linearity (R≥0.9991) and a broad linear range for all studied PAHs. The proposed analytical procedure exhibited a good precision level with relative standard deviations below 15% for all analytes. Quantification limits between 0.7 and 2.3 µg L(-1) and 0.16 and 3.90 ng L(-1) were obtained for compounds analyzed by UV (acenaphtylene, cyclopenta[c,d]pyrene and benzo[j]fluoranthene) and fluorescence, respectively. Finally, the proposed method was applied to the determination of PAHs in different real tap, river and wastewater samples.

[Distribution of polycyclic aromatic hydrocarbons in water and sediment from Zhoushan coastal area, China].

The spatial and temporal distribution of 16 polycyclic aromatic hydrocarbons (PAHs) has been investigated in water and sediments of Zhoushan coastal area every two months in 2012. The concentrations of total PAHs ranged from 382.3 to 816.9 ng x L(-1), with the mean value of 552.5 ng x L(-1) in water; whereas it ranged from 1017.9 to 3047.1 ng x g(-1), with the mean value of 2 022.4 ng x g(-1) in sediment. Spatial distribution showed that Yangshan and Yanwoshan offshore area had the maximum and minimum of total PAHs contents in water, while the maximum and minimum occurred at Yangshan and Zhujiajian Nansha offshore area in sediment. Temporal distribution revealed that total PAHs contents in water reached the maximum and minimum values in October and June, however in sediments these values were found in August and June, respectively. The PAHs pollution was affected by oil emission, charcoal and coal combustion. Using the biological threshold and exceeded coefficient method to assess the ecological risk of PAHs in Zhoushan coastal area, the result showed that sigma PAHs had a lower probability of potential risk, while there was a higher probability of potential risk for acenaphthylene monomer, and there might be ecological risk for acenaphthene and fluorene. Distribution of PAHs between sediment and water showed that Zhoushan coastal sediment enriched a lot of PAHs, meanwhile the enrichment coefficient (K(d) value) of sediment in Daishan island was larger than that in Zhoushan main island.

Copper(II) complexes of bis(aryl-imino)acenaphthene ligands: synthesis, structure, DFT studies and evaluation in reverse ATRP of styrene.

Two new Ar-BIAN Cu(II) complexes (where Ar-BIAN = bis(aryl-imino)acenaphthene) of formulations [CuCl2(Mes-BIAN)] (1) (Mes = 2,4,6-Me3C6H2) and [CuCl2(Dipp-BIAN)] (2) (Dipp = 2,6-iPr2C6H3) were synthesised by direct reaction of CuCl2 suspended in dichloromethane with the respective ligands Mes-BIAN (L1) and Dipp-BIAN (L2), dissolved in dichloromethane, under an argon atmosphere. Attempts to obtain these compounds by solubilising CuCl2 in methanol and adding a dichloromethane solution of the corresponding ligand, under aerobic conditions, gave also compound 1, but, in the case of L2, the Cu(I) dimer [CuCl(Dipp-BIAN)]2 (3) was obtained instead of compound 2. The compounds were fully characterised by elemental analyses, MALDI-TOF mass spectrometry, FT-IR, (1)H NMR and EPR spectroscopic techniques. The solid-state molecular structures of compounds 1-3 were determined by single crystal X-ray diffraction, showing the expected chelation of the Ar-BIAN ligands and two chloride ligands completing the coordination sphere of the Cu(II) centre. In the case of the complex 1, an intermediate coordination geometry around the Cu(II) centre, between square planar and tetrahedral, was revealed, while the complex 2 showed an almost square planar geometry. The structural differences and evaluation of energetic changes were rationalised by DFT calculations. Analysis of the electrochemical behaviour of complexes 1-3 was performed by cyclic voltammetry and the experimental redox potentials for Cu(II)/Cu(I) pairs have been compared with theoretical values calculated by DFT in the gas phase and in dichloromethane and methanol solutions. The complex 1 exhibited good activity in the reverse atom transfer radical polymerisation (ATRP) of styrene.

Characteristics of nano-/ultrafine particle-bound PAHs in ambient air at an international airport.

Concentrations of 22 polycyclic aromatic hydrocarbons (PAHs) were estimated for individual particle-size distributions at the airport apron of the Taipei International Airport, Taiwan, on 48 days in July, September, October, and December of 2011. In total, 672 integrated air samples were collected using a micro-orifice uniform deposition impactor (MOUDI) and a nano-MOUDI. Particle-bound PAHs (P-PAHs) were analyzed by gas chromatography with mass selective detector (GC/MSD). The five most abundant species of P-PAHs on all sampling days were naphthalene (NaP), phenanthrene (PA), fluoranthene (FL), acenaphthene (AcP), and pyrene (Pyr). Total P-PAHs concentrations were 152.21, 184.83, and 188.94 ng/m(3) in summer, autumn, and winter, respectively. On average, the most abundant fractions of benzo[a]pyrene equivalent concentration (BaPeq) in different molecular weights were high-weight PAHs (79.29 %), followed by medium-weight PAHs (11.57 %) and low-weight PAHs (9.14 %). The mean BaPeq concentrations were 1.25 and 0.94 (ng/m(3)) in ultrafine particles (<0.1 µm) and nano-particles (<0.032 µm), respectively. The percentages of total BaPeq in nano- and ultrafine particulate size ranges were 52.4 % and 70.15 %, respectively.

Efficiency of butyl rubber sorbent to remove the PAH toxicity.

Large amounts of polycyclic aromatic hydrocarbons (PAHs) have been released to the marine environment as a result of oil spills and from other sources including wastewaters, surface runoff, industrial processes, atmospheric deposition, biosynthesis, and natural events such as forest fires. PAHs have been known to affect a variety of biological processes and can be potent cell mutagens/carcinogens and toxic. In this study, PAH toxicity removal was investigated by using a novel macroporous butyl rubber (BR) sorbent. To find out the toxicity removal efficiency of the sorbents, the toxicity tests with Vibrio fisheri (luminescence bacteria) and Phaeodactylum tricornutum (marine algae) were applied to the acenaphthene (Ace) and phenanthrene (Phen) solutions in seawater (Ace: 500- 1000 µg/L; Phen; 100-1000 µg/L) before and after sorbent applications. Additionally, lysosomal stability and filtration rate biomarker techniques were applied to the mussels (Mytilus galloprovincialis) exposed to 1000 µg/L Phen solution and bioaccumulation was measured. The results showed that the toxicity of the PAH solutions decreased 50-100 percent depending on the concentration of the solutions and organisms. Phaeodactylum was found as the most sensitive organism to Phen and Ace. Since the application of BR sorbent removed the Phen from the solution, the bioaccumulated Phen amount in the mussels decreased accordingly.

Atmospheric concentrations and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in remote, rural village and urban areas of Beijing-Tianjin region, North China.

Forty passive air samplers were deployed to study the occurrence of gas and particulate phase PAHs in remote, rural village and urban areas of Beijing-Tianjin region, North China for four seasons (spring, summer, fall and winter) from 2007 to 2008. The influence of emissions on the spatial distribution pattern of air PAH concentrations was addressed. In addition, the air-soil gas exchange of PAHs was studied using fugacity calculations. The median gaseous and particulate phase PAH concentrations were 222 ng/m³ and 114 ng/m³, respectively, with a median total PAH concentration of 349 ng/m³. Higher PAH concentrations were measured in winter than in other seasons. Air PAH concentrations measured at the rural villages and urban sites in the northern mountain region were significantly lower than those measured at sites in the southern plain during all seasons. However, there was no significant difference in PAH concentrations between the rural villages and urban sites in the northern and southern areas. This urban-rural PAH distribution pattern was related to the location of PAH emission sources and the population distribution. The location of PAH emission sources explained 56%-77% of the spatial variation in ambient air PAH concentrations. The annual median air-soil gas exchange flux of PAHs was 42.2 ng/m²/day from soil to air. Among the 15 PAHs measured, acenaphthylene (ACY) and acenaphthene (ACE) contributed to more than half of the total exchange flux. Furthermore, the air-soil gas exchange fluxes of PAHs at the urban sites were higher than those at the remote and rural sites. In summer, more gaseous PAHs volatilized from soil to air because of higher temperatures and increased rainfall. However, in winter, more gaseous PAHs deposited from air to soil due to higher PAH emissions and lower temperatures. The soil TOC concentration had no significant influence on the air-soil gas exchange of PAHs.

Impact of forest fires on PAH level and distribution in soils.

Surface (0-5 cm) and subsurface (-5 to 15 cm) soils from burned forest areas in South of France were analyzed to determine contents of 14 priority polycyclic aromatic hydrocarbons (PAHs) and their distribution profile. The sampling procedure allowed us to study the effect of the frequency of fire as well as the influence of the time elapsed since the last fire. The contribution of forest fires to the content of PAHs in soils was demonstrated, as well as the decrease of their total level with time. The hypothesis is that a natural remediation takes place a few years after the last fire event. The lowest molecular weight studied PAHs (naphthalene, acenaphtene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene) appear to be the major ones produced by forest fire. Naphtalene levels are remarkably high in burned soils (more than 70 µg kg(-1), i.e. more than 20 times higher than in the control soils) and still remain important years after the last fire event. The time elapsed since the last fire appears to be a more influencing factor than the fire frequency. The index defined from the PAH levels shows values reflecting the time elapsed since the last fire.

Polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Liaodong Bay, Bohai Sea, China.

MATERIALS AND METHODS: The levels and possible sources of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated in the surface sediments of Liaodong Bay, Bohai Sea, China. RESULTS: The sum of 16 PAHs (∑PAH(16)) concentrations varied from 144.5 to 291.7 ng/g, with a mean value of 184.7 ng/g, indicating low PAH levels compared with reported values for other bays and rivers in China and developed countries. High concentrations of PAHs were observed in the Luan River Estuary and in the vicinity of Qinhuangdao, implying that sewage from the Luan River and shipping activities are important sources of PAHs in Liaodong Bay. CONCLUSION: An ecological risk assessment of PAHs, based on the effect range-low quotients, indicated that adverse biological effects caused by acenaphthene occasionally may take place in the sediments of Liaodong Bay. PAH source identification suggested that PAHs in most sediments were mainly from incomplete combustion of grass, wood, and coal. At other stations near the Luan River Estuary, both petrogenic and pyrogenic inputs were significant, and the petroleum-derived PAHs were mainly from shipping activities and discharge of pollutants via rivers.

Temperature-dependent sorption of polycyclic aromatic hydrocarbons on natural and treated sediments.

In aqueous environment temperature is considered to play a significant role in the sorption process of polycyclic aromatic hydrocarbons (PAHs) and its influence on the sorption equilibrium is indicative of sorption energies and mechanisms. In this study, sorptions of five PAHs on three heterogeneous sorbents including one river sediment (YHR), one estuary sediment (YRD) and one treated sediment with organic matter removed (IM) were carried out at a range of temperature from 5 °C to 35 °C. Stronger sorptions were observed at lower temperatures, with the equilibrium sorption coefficient Kd increasing 2-5 times as the temperature decreases 30 °C. The increase of Kd value was attributed primarily to the change of PAH water solubility, which predicted 40-75% of the increase of Kd in the sorption process. To provide insight into the sorption mechanism, enthalpy change (ΔHS) for the sorption process was calculated and the values were observed to be negative for all of the interactions, suggesting that the exothermal sorption of PAHs inversely dependents on temperature. Based on the values of ΔHS, van der Waals forces were inferred as the main sorption mechanism for the PAHs, especially on the YHR sediment which contained more organic matter. For sorption of larger size PAHs on the sorbents with low organic matter, specific interactions were deduced to contribute to the overall sorption.

Simultaneous fluorimetric determination of the biodegradation processes of dissolved multi-component PAHs.

A fluorimetric method for simultaneous determination of dissolved acenaphthylene (Ace) phenanthrene (Ph) and pyrene (Py), mixed in an aqueous mineral salts medium (MSM), was developed. The linear ranges for determination of Ace, Ph and Py dissolved in the mixture were 4.00 x 10(-6) to 3.00 x 10(-3)g/L, 2.00 x 10(-6) to 1.00 x 10(-3)g/L and 7.00 x 10(-7) to 1.00 x 10(-4)g/L. The limits of detection for Ace, Ph and Py were 8.53 x 10(-7), 4.98 x 10(-7) and 6.01 x 10(-8)g/L and the relative standard deviations 1.05%, 1.62% and 1.16% (n=8), respectively. Satisfactory results were obtained when this method was used to simultaneously study the biodegradation processes of mixtures of dissolved Ace, Ph and Py in an MSM aqueous solution.

Comparison of thin-film microextraction and stir bar sorptive extraction for the analysis of polycyclic aromatic hydrocarbons in aqueous samples with controlled agitation conditions.

The characterization of a poly(dimethylsiloxane) (PDMS) thin film for active extraction of some polycyclic aromatic hydrocarbons was investigated in both a 1-L aqueous solution and a flow-through system. The thin film was attached to an electric bench-drill at a constant rotation speed for constant agitation and fast extraction. The performance of a PDMS-coated stir bar at a constant stirring speed was also investigated. The comparison showed that the extraction rate was much higher when using the thin film than the stir bar, and that the equilibration time was greatly shortened due to the larger surface area/volume ratio of the thin film. The extraction rate was roughly proportional to surface area of the extraction phase during the initial stage of the extraction process; the amount of analyte extracted was proportional to the ratio of the extraction phase between the thin film and the stir bar. Different agitation and stirring rates of the thin film and stir bar were applied for extraction, revealing that extraction efficiency can be improved by increasing rotation rate. The application of rotated thin film in the field proved it is a valid and easily operated method for the determination of polycyclic aromatic hydrocarbons (PAHs) in a campus river. However, the stir bar is not as convenient as a thin film in field sampling.

Simultaneous monitoring of profiles of polycyclic aromatic hydrocarbons in contaminated air with semipermeable membrane devices and spruce needles.

Gaseous emissions of combusted electronic scrap, PVC, carpet and wood were monitored for polycyclic aromatic hydrocarbons (PAHs) by simultaneous use of semipermeable membrane devices (SPMDs) and shoots of spruce needles (Picea abies). It was found that phenanthrene, acenaphthylene and fluorene were the dominating PAHs in all samples. SPMDs and needles mainly sequestered PAH associated with the vapor phase. Particle-bound PAHs were only detected in small amounts, at which the needles tended to uptake more of these compounds in comparison to the SPMDs. Nevertheless, the logarithm of the concentrations of PAHs analyzed in both passive samplers after the same sampling period exhibited a significant linear correlation with correlation coefficients larger than 0.8073. SPMDs and spruce needles can complement each other in passive air sampling for compounds with a preference to the gas phase rather than aerosols.